Tiananmen Square's 20th Anniversary: Whither Hollywood?

Why has there never been a movie made about the Tiananmen Square massacres?

I have no good answer to this question. This year marks the 20th anniversary of the catastrophic, seminal event in the history of China and Chinese-US relations. One would think that such a huge event would have produced several movies by now. The story is incredible enough: a group of several thousand unhappy college students put together a beautiful, emotional protest against their oppressive government, using the United States as the role model.

This uprising may have been crushed by the ruthless Chinese government forces, but history will not turn its back on those brave young men and women who risked, and lost, their lives. Why has Hollywood?